diff --git a/lang_agent/components/conv_store.py b/lang_agent/components/conv_store.py
index f4b7e6d..9986684 100644
--- a/lang_agent/components/conv_store.py
+++ b/lang_agent/components/conv_store.py
@@ -1,10 +1,9 @@
 import psycopg
-from uuid import UUID
 from typing import List, Dict, Union
 from enum import Enum
 import os
 
-from langchain_core.messages import HumanMessage, AIMessage, ToolMessage, BaseMessage
+from langchain_core.messages import HumanMessage, AIMessage, ToolMessage, SystemMessage, BaseMessage
 
 class MessageType(str, Enum):
     """Enum for message types in the conversation store."""
@@ -19,22 +18,13 @@ class ConversationStore:
             raise ValueError("CONN_STR is not set")
         self.conn_str = conn_str
 
-    def _coerce_conversation_id(self, conversation_id: Union[str, UUID]) -> UUID:
-        if isinstance(conversation_id, UUID):
-            return conversation_id
-        try:
-            return UUID(conversation_id)
-        except (TypeError, ValueError) as e:
-            raise ValueError("conversation_id must be a UUID (or UUID string)") from e
-    
     def add_message(
         self,
-        conversation_id: Union[str, UUID],
+        conversation_id: str,
         msg_type: MessageType,
         content: str,
         sequence: int,   # the conversation number
     ):
-        conversation_id = self._coerce_conversation_id(conversation_id)
         with psycopg.connect(self.conn_str) as conn:
             with conn.cursor() as cur:
                 # DB schema only supports these columns:
@@ -47,12 +37,11 @@ class ConversationStore:
                     (conversation_id, msg_type.value, content, sequence),
                 )
     
-    def get_conv_number(self, conversation_id: Union[str, UUID]) -> int:
+    def get_conv_number(self, conversation_id: str) -> int:
         """
             if the conversation_id does not exist, return 0
             if len(conversation) = 3, it will return 3
         """
-        conversation_id = self._coerce_conversation_id(conversation_id)
         with psycopg.connect(self.conn_str) as conn:
             with conn.cursor() as cur:
                 cur.execute("""
@@ -62,8 +51,7 @@ class ConversationStore:
                     """, (conversation_id,))
                 return int(cur.fetchone()[0])
     
-    def get_conversation(self, conversation_id: Union[str, UUID]) -> List[Dict]:
-        conversation_id = self._coerce_conversation_id(conversation_id)
+    def get_conversation(self, conversation_id: str) -> List[Dict]:
         with psycopg.connect(self.conn_str) as conn:
             with conn.cursor(row_factory=psycopg.rows.dict_row) as cur:
                 cur.execute("""
@@ -75,6 +63,7 @@ class ConversationStore:
                 return cur.fetchall()
     
     def record_messages(self, conv_id:str, inp:List[BaseMessage]):
+        inp = [e for e in inp if not isinstance(e, SystemMessage)]
         curr_len = self.get_conv_number(conv_id)
         to_add_msg = inp[curr_len:]
         for msg in to_add_msg: